I have decided to produce a pcboard with the Super A circuit (transistorized) included withing the circuit board.... so, it will not be an external circuit to connect to the main pcboard with wires or flat cables.

Juan Vargas is producing the layout and this may take several months to be ready...but we have already started.

This is because sonics is fine and there's a lot of guys that loves Class A, despite this Dx Super A is a little bit different... stand by current is smaller and the power while in class A is not that big...but sonics to low levels have really increased in quality (and also a little bit mufled at low levels as class A use to be in my point of view).

Juan and me, we are deciding if we gonna use Mitchel's layout to be modified to if we gonna make (Juan will make) a new one without the use of Mitchel's layout to the Dx Blame ST (green Brazilian group buy ones).

Here you see the first study made by Juan Vargas (Vargas Mongo from Puerto Rico), and in the next post i will show you Mitchel's layout.

Modifications will be the inclusion of the Dx Super A circuit... a couple of transistors, capacitors, diodes and resistors.... just that..but this produces a lot of hard work and take a lot of time if we want to make things simetrycal and aligned.

preference to work together Mitchel and Juan, as we are already tuned related a lot of details... you can make even better layout, but it will not be "latine" in it's soul.... this one is "Brazilian" in it's soul... latine but without advertisements printed into the pcboard.

Circuit will be adjusted to 42 plus 42 volts supplies...power can reach 90/180 watts RMS if you accept some small distortion (8 and 4 ohms)...it will have two output pairs, and we gonna use 2SC5200 and complementary, BD139 and complementary and BC546 and complementary.

I will not make it customized to other voltages and i have no intention to run group buy...but we will give you black and white layout (copper tracks) in order for you to etch at home if you want

I am playing with the Dx Blame with Dx Super A module (published in this forum)... you can see in this video:

I am uploading videos with testings made...... next week i will explain (again) how this circuit operates.

Here you have the schematic that played full power by 6 hours long...no troubles.

Supply voltage is 42 plus 42 volts

Output voltage is 28VAC RMS at 8,4 and 2 ohms

Power output is 100/200 and 400W RMS

Distortion to 100W at 8 ohms is 0.001% (THD)

Distortion to 400W at 2 ohms is 0.028% (THD)

Sensitivity.... 800 milivolts to full power

Input impedance: 56K aproximately

Stand by current: 250mA

Circuit efficiency is around 55%....so, you need a little bit twice the output power to obtain full power swing... more or less 200VA to 100W, 200VA to 200W and 800VA to 400W (aproximately)

Heatsink should be huge and a fan installed will be a very good idea.

Operation to 2 ohms is critical, so, do not use power transformer above 30 plus 30 volts AC because this will put the output at risk..use the strongest and more modern output transistors you can find...these ones suggested are no good for 2 ohms operation.

Compared to the Dx Blame St i have made modifications...the inclusion of a 1K resistor in series with the first VAS colector, the gain resistor now is 1200 ohms, the input resistor that sets the input impedance is 56K and this will allow you to use 680n capacitors to the input.... maximum is 1uf in the input and please try units with small insulating voltage..do not use big ones to 250 volts or more...better to use 6 volts of insulating voltage there...or even less..capture electrolitic condenser from a junk... small cassete players, small radios.... these ones have small insulating voltage condenser and capacitors due to their supply voltage that is low.

A future video will explain, a little bit more technically, how this circuit works with current charts....i am sure you will understand if you already do not know how the stuff works (i doubt that).

Dx amplifiers are made for you, it is not a business, anything is to be sold, usually offered in group buys and for free to the DIY community ... we provide layout for you to etch at your home and some help... we even explain some basic things we know (only basic things).

The Corporation has not existence in the real world, it is just a name, an Union of audiophiles (the best ones) that loves to build their own amplifiers, tweak and adjust....it is constituted by these guys that usually cooperated producing board layout (I do not know how to do, i do not want to learn how to do pcboard layout, i am unable, i want to continue to be unable and dumb about that) and they usually help in several other ways too.

These amplifier are usually based in Doctor Self designs, in special the Blameless...they are modified, tweaked for sonics and offered as a tested amplifier already built by hundreds of forum folks.... more than 300 units in Brasil and more or less 600 units wide world...all them for free!

I am not an engineer, nor a designer....i am a self made man that loves audio electronics and use to be building audio amplifiers... thousands made (half of them exploded in my face)...my expertise is to force things to work and to build "Franksteins"... using several different designer's stages together.... always build and tested, sometimes tortured...it is something you can trust will not bust in your face.

This one was tested yesterday..the whole day...from 7AM to 8PM.... passed!

I am 52 years doing this stuff (buiding units) and i have made several studies including in Sony Japan but all i know (reality) is due to the practical exercise of try and error and basic ohms law calculation together imagination, love and passion by audio electronics.

The point is to produce good sound with cheap speakers...there's no point to me to obtain good sound with an acoustic prepared home spending thousands of dollares to buy exotic speakers...i want good sound playing with standard, general, common speakers...cheap ones...and to make my units not spending too much money for it.

These last years i had several good guys helping me.... Daniel from Croatia (now a days a pipe maker), a lovely dutch that make beer can, an awesome engineer that produces hand made layouts (Taj), a Oil man from Petrobrás, Miguel Nabuco (Mitchel), an expert in computers from Germany (Rudi), a guy filled with passion by audio from mid east (Metal), a clever brazilian from São Paulo (Herman), a kind guy from Puerto Rico (Juan) and several many others that gave me a hand and i have to thank all them by the enjoyment to work together people that has passion for audio.